You can also CAST a date to a string to extract components using SUBSTRING or make up another date.

You can also CAST a date to a string to extract components using SUBSTRING or make up another date.

<source lang='sql' class='def'>

<source lang='sql' class='def'>

−

SELECT CAST(population/1000000 AS DECIMAL(8,1)) AS a

+

SELECT CAST(population/1000000

+

AS DECIMAL(8,1)) AS a

,population/1000000 AS b

,population/1000000 AS b

FROM bbc

FROM bbc

Revision as of 11:54, 13 July 2012

Compatibility

CAST(expr AS type)

Engine

OK

Alternative

ingres

Yes

mysql

Yes

oracle

Yes

postgres

Yes

sqlserver

Yes

CAST

CAST allows you to convert from one type to another.

Often a CAST is implicit - for example if you concatenate a string with a number the number will be automatically changed to a string. However sometimes you need to make the CAST explicit.

CAST(expr TO type)

In this example we get the population in millions by casting the floating point value to DECIMAL(8,1) - this ensures one decimal place of accuracy.
You can also CAST a date to a string to extract components using SUBSTRING or make up another date.